Positive spring force actuator

ABSTRACT

When locking a medical imaging device detector in position to generate a medical image, an articulating arm includes top and bottom portions, coupled to a gantry and to a distal portion that is coupled to a detector. The top and bottom portions each include an over-the-center bell crank locking mechanism with a shank couple to a central handle. Each shank includes a pair of flanges that are coupled to a pair of actuators by both a pivot pin and a spring mechanism. Each actuator is coupled to a crank. When the handle is rotated to a locked position, a sliding lock extends to lock the articulating arm in position relative to the gantry, and a lever arm is extended to cause a shaft to rotate. Rotation of the shaft actuates a sliding pin linkage, which urges a pair of pins outward to lock the articulating arm in position relative to the detector.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT application number PCT/IB2008/054478 filed Oct. 29, 2008 which claims the benefit of U.S. provisional application Ser. No. 61/061,237 filed Jun. 13, 2008 and U.S. provisional application Ser. No. 60/985,789 filed Nov. 6, 2007. PCT application number PCT/IB2008/054478 filed Oct. 29, 2008 is incorporated herein by reference in its entirety. U.S. provisional application Ser. No. 61/061,237 filed Jun. 13, 2008 and U.S. provisional application Ser. No. 60/985,789 filed Nov. 6, 2007 are incorporated herein in their entirety.

DESCRIPTION

The present innovation finds particular application in diagnostic imaging systems, particularly involving cone-beam computed tomography (CT) and single photon emission computed tomography (SPECT). However, it will be appreciated that the described technique may also find application in other imaging systems, other medical scenarios, or other medical techniques.

Typical commercial system designs, such as Philips Precedence, Philips Gemini, Siemens Symbia, etc., that combine both nuclear medicine (NM) and X-ray CT modalities are configured in an in-line geometry. In this configuration, a common patient table extends between two imaging field-of-view (FOV) regions that are separated in the axial direction by the space between the NM and CT gantries.

In other commercial system designs, such as the GE Hawkeye, an x-ray source and CT detector are mounted a common gantry with the NM detectors, but are still separated in the axial direction. Others have proposed concepts using flat panel detectors mounted on a common gantry. When the CT and NM detectors are axially displaced, there is axial movement and temporal offset between NM and CT data acquisitions. This raises issues concerning subject motion between the NM and CT data acquisitions and alignment.

Reconstruction for asymmetric detector configurations has been published for extending the FOV for SPECT detector systems using radiation sources. Radiation therapy systems have integrated imaging to more precisely target tumors using flat panels that have been configured to support a larger imaging FOV. Additionally, pre-clinical systems have used an asymmetric detector geometry that makes use of volume CT reconstruction.

When combining two different technologies together, such as a SPECT Gantry with an X-Ray Gantry (C-Arm) several challenges arise. Integrating these two systems into one gantry involves additional packaging constraints and SPECT detector motions that can cause interference with X-Ray components. For instance, once deployed, a flat panel X-ray detector needs to be accurately positioned and held stable to reduce artifacts. Additionally, it is desirable that deployment is repeatable at the same position.

The present application provides new and improved articulating arm locking assembly that overcomes the above-referenced problems and others.

In accordance with one aspect, a bell-crank locking mechanism includes a first actuator coupled to a first flange via a first spring mechanism, and to a second flange by a first pivot pin, and a second actuator coupled to the second flange via a second spring mechanism, and to the first flange by a second pivot pin. The mechanism further includes a shank coupled to the first and second flanges, a pin coupled to each actuator, a crank coupled to each pin, and a sliding lock coupled to a first crank. The mechanism further includes a first lever arm couple coupled to a second crank, and a shaft coupled to the lever arm and to a second lever arm that is coupled to a pin linkage. Additionally, the mechanism includes first and second pivot links coupled to the pin linkage, which urge first and second locking pins into a locked position when activated by the second lever arm. A handle rotates the shank from an unlocked position in which the pins and the first and second cranks are in a retracted position, through a center position of the pins in which the cranks reach maximum extension and the spring mechanisms are at maximum compression, to an over-center locked position in which the spring mechanisms are partially compressed.

In accordance with another aspect, a lockable articulating arm includes a top portion and a bottom portion, each of which includes a positive spring-force locking mechanism having a first actuator coupled to a first flange via a first spring mechanism and to a second flange by a first pivot pin. The locking mechanism further includes a second actuator coupled to the second flange via a second spring mechanism and to the first flange by a second pivot pin, wherein the flanges are coupled to a shank, which is further coupled to a handle. Each actuator is coupled to a respective pin. A first bell crank is coupled to a first pin on the first actuator and extends a sliding lock locks the articulating arm relative to a gantry when the handle is in the locked position. A second bell crank is coupled to a second pin on the second actuator and causes at least one locking pin to be extended to lock the articulating arm relative to a detector head when the handle is in the locked position. The second bell crank actuates a shaft that extends a sliding pin linkage that urges a pair of locking pins in a distal portion thereof into a locked position, thereby locking the articulating arm relative to the detector head.

In accordance with yet another aspect, a method of locking a device in each of a stowed position and an extended position includes applying approximately 10 pounds of force to rotate a handle on an articulating arm approximately 180° from a locked position to an unlocked position, moving the detector head from a stowed position to an extended position, and applying approximately 12-14 pounds of force to rotate the handle from the unlocked position to the locked position. Rotating the handle effectuates rotation of a pair of locking mechanisms, each of which extends a sliding lock to lock the articulating arm in position at a mounted end, and extends a lever arm to effectuate movement of a sliding pin linkage that extends a pair of locking pins to lock the articulating arm in position at a device end.

One advantage is that the input force is converted into low and/or high independent, multi-directional forces.

Another advantage resides in lock-out of output forces within a 180° turn of the input force.

Another advantage resides in reducing backlash, fatigue, tolerance play, wear, misalignment and under/over travel of the articulating arm.

Another advantage resides in elimination of the snapping or jerking motion that results from the use of conventional compression or tension springs.

Another advantage resides in automated locking of a flat panel X-ray detector.

Still further advantages of the subject innovation will be appreciated by those of ordinary skill in the art upon reading and understanding the following detailed description.

The innovation may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating various aspects and are not to be construed as limiting the invention.

FIG. 1 illustrates an imaging system includes a subject support, such as a table or couch, which is selectively positionable up and down to position a subject being imaged or examined at a desired location, for instance, so that regions of interest are centered about a longitudinal axis.

FIG. 2A diagrammatically illustrates a front view of the integrated hybrid system, which includes two nuclear detectors, X-ray or CT source, and flat panel X-ray or CT detector that is mounted asymmetrically to a common rotation center of the gantry.

FIG. 2B diagrammatically illustrates a side view of the integrated hybrid system of FIG. 2A, wherein the imaging FOVs between the two systems is common or coincident, requiring little or no movement of the patient, providing commonly registered images due to the similar imaging planes.

FIG. 2C diagrammatically illustrates another side-view of the system of FIG. 2B, wherein the CT source and detector have been moved to a retracted position along the longitudinal axis.

FIG. 2D diagrammatically illustrates a side view of the gantry wherein the CT source moves longitudinally parallel to a central longitudinally axis through the gantry, while emitting an X-ray cone beam through the VOI.

FIG. 2E diagrammatically illustrates a side view of another embodiment of the system, wherein the CT X-ray source and flat panel detector are in an in-line configuration relative to the nuclear detector heads. In this embodiment, a volume of interest (VOI) can be imaged using the nuclear detector heads and the CT source and detector sequentially (in either order).

FIG. 3 is an illustration of another embodiment of the imaging system with a collimator and filter device for directing all or a portion of a cone-shaped X-ray beam to an offset flat panel detector.

FIG. 4 illustrates the system configured in a geometry with the NM detector at a 90° angle that is typically used during a nuclear cardiology exam.

FIG. 5 illustrates another embodiment of the system, wherein the nuclear detectors (e.g., SPECT or PET), the CT source, and the flat panel detector are movably mounted on tracks that facilitate positioning the devices at desired locations during CT and/or nuclear scans and moving components that are not currently in use out of the way of those that are.

FIG. 6 is a perspective view of the system, wherein the flat panel detector is in its operational position, extended outward on an extender that is lockably coupled to a mount that couples the extender and flat panel detector to the gantry.

FIG. 7 is a perspective view of an automatic locking mechanism for locking the flat panel detector in one or more positions, shown with the extender arm in its extended position.

FIG. 8 illustrates the automatic locking mechanism for the flat panel CT detector in its stowed position.

FIG. 9 illustrates the automatic locking mechanism in its fully extended position.

FIG. 10 illustrates the hinge portion of the automatic locking mechanism when the extender arm is in its extended position.

FIG. 11 is an illustration of the gantry with the nuclear detectors and the radiation source, which is shown opposite the flat panel X-ray detector.

FIG. 12 is an illustration of the gantry, showing the nuclear detectors and the radiation source with the flat panel detector deployed.

FIG. 13A illustrates the flat panel detector stored in a folded position against the extender arm, which is also in a folded stowed position.

FIG. 13B illustrates the flat panel detector folded or rotated outward from the extender arm about a first pivot point or hinge.

FIG. 13C illustrates the flat panel detector and the extender arm in fully extended positions, having been rotated outward from the stowed position to an operational position.

FIG. 13D illustrates the flat panel detector and the extender arm in a locked extended position.

FIG. 14 illustrates an embodiment of the system with the lockable extender arm and flat paned detector assembly in an extended or operational position.

FIG. 15 illustrates a positive force locking mechanism that includes a pair of independent spring-forced actuators.

FIG. 16 is an exploded view of the locking mechanism, which is employed in a bell crank type mechanism adapted to a handle (not shown) in a unique, miniaturized fashion the allows the handle to be used within a compact zone and with minimal turning for locking and unlocking.

FIG. 17 illustrates an articulating arm linkage assembly, which includes the locking mechanism.

FIG. 18 illustrates the articulating arm in a locked state, wherein the sliding cam lock linkage has been pivoted into a locked position about the locking mechanism.

FIG. 19 illustrates the articulating arm with the handle positioned approximately halfway between the locked and unlocked positions.

FIG. 20 illustrates the articulating arm, coupled to a gantry by an axle or pin at one end and to a detector head by an axle or pin at the other end.

FIG. 21 illustrates the articulating arm coupled to the gantry and the detector head.

FIG. 22 illustrates the articulating arm coupled to the gantry and the detector head, with two hash lines drawn therethrough.

FIG. 23 illustrates the articulating arm through section A-A of FIG. 22.

FIG. 24 illustrates the articulating arm through section B-B of FIG. 22.

The systems and methods described herein relate to combining a cone-beam CT (CBCT) source with an offset flat panel detector and nuclear imaging heads in a single patient imaging device. By using an offset flat panel detector, the size of the detector can be minimized, as compared to a full-sized CT detector, thereby occupying less space and permitting greater freedom of movement of the nuclear imaging heads. Nuclear imaging provides physiological process and/or functional information that can be used for diagnosis, to assess the effectiveness of therapy, etc. The addition of another modality, such as CBCT that is co-registered is useful in improving the clinical confidence of the reader. Additionally, the CBCT information can be used to correct for attenuation of emission data, improving the quantitative accuracy and the quality of the images.

Other features relate to a locking mechanism that ensures that the flat panel detector stays in place during CBCT scans and stows out of the way when the CBCT source is not in use, such as during a nuclear imaging (NM) scan or during system downtime.

With reference to FIG. 1, an imaging system 10 includes a subject support 12, such as a table or couch, which is selectively positionable up and down to position a subject being imaged or examined at a desired height, for instance, so that a volume of interest of the patient is centered about a longitudinal axis of the imaging system. The table includes a pallet 14 that is moveable parallel to the longitudinal axis through a rotatable gantry 16, such that the volume of interest (VOI) of the patient can be translated into the field of view (FOV) of the imaging system for imaging by nuclear detector heads 18 (e.g., gamma cameras or the like) and/or by a CBCT X-ray source 20 and a flat panel CBCT or X-ray detector 22. A motive power source (not shown), such as a motor, selectively drives the pallet parallel to the longitudinal axis to position the VOI in the FOV. Detected patient image data (e.g., nuclear and/or CT data) is received by a workstation (not shown), which includes appropriate hardware and software for performing image reconstruction and the like to generate images for viewing by an operator on a monitor 24.

An inner gantry structure 26 is rotatably mounted on the outer gantry structure 28 for stepped or continuous rotation. The nuclear detector heads 18 rotate as a group about the subject, when received, with the rotation of the rotating gantry structure 26. The detector heads are radially, circumferentially, and laterally adjustable to vary their distance from the subject and spacing on the rotating gantry 26 to position the detector heads in any of a variety of angular orientations about, and displacements from, the central axis. For example, separate translation devices, such as motors and drive assemblies, are provided to independently translate the detector heads radially, circumferentially, and laterally in directions tangential to the subject (e.g., along linear tracks or other appropriate guides). The embodiments described herein employing two detector heads can be implemented on a two detector system, a three detector system, or the like. Likewise, the use of three-fold symmetry to adapt the illustrated embodiments to a three detector system is also contemplated.

In one embodiment, the nuclear detector heads are SPECT detector heads. In SPECT imaging, a projection image representation is defined by the radiation data received at each coordinate on the detector head. In SPECT imaging, a collimator defines the rays along which radiation is received.

In another embodiment, the nuclear detector heads are positron emission tomography (PET) detector heads. In PET imaging, the detector head outputs are monitored for coincident radiation events on two heads. From the position and orientation of the heads and the location on the faces at which the coincident radiation is received, a ray or line of response (LOR) between the coincident event detection points is calculated. This LOR defines a line along which the radiation event occurred. In both PET and SPECT, the radiation data from a multiplicity of angular orientations of the heads is then reconstructed into a volumetric image representation of the volume of interest.

The CBCT source 20 can be segmented into a plurality of regions such that only a portion of the field of view (FOV) is imaged at a time during a scan, for instance, by employing a collimator and/or an axial filter suitable for CT imaging, as discussed below with regard to FIG. 3.

The CBCT source 20 rotates around the FOV such that both CT and emission imaging FOVs are coincident or overlapping with limited or no movement of the pallet 14. The flat panel radiation detector 22 is placed in an asymmetric geometry relative to the rotation center so that the CT FOV is sufficient to image patients without truncation. Additionally, the flat panel detector facilitates generating high-resolution radiographic data that can be interpreted as radiograms. Thus, system 10 is a multi-modality system that eliminates or reduces registration problems between nuclear imaging (e.g., SPECT, PET, etc.) and CT or other modality images, since the displacement between the two imaging planes is significantly reduced or eliminated compared to in-line systems. This also reduces the requirements on the room size for a combined scanner, since the patient support does not need to be extended to different FOVs of two separate imaging systems. Complexity and cost of the site preparation is thereby reduced, and retroactive installation of SPECT/CT or PET/CT systems in existing facilities is facilitated.

By using an asymmetric detector geometry, the flat panel detector 22 can be reduced in size to accommodate conventional motions of the nuclear detectors 18, mitigating clearance issues that may arise if a larger CT detector were used. Furthermore, no additional cost is associated with the patient table since no modification is required thereto over existing SPECT or PET imaging table configurations (e.g., because the nuclear imaging FOV and the CT imaging FOV are coincident). Furthermore, the FOV of the CT can be increased (e.g., doubled to approximately 50 cm or more), allowing the scanning of large patients without truncation. Additionally, nuclear detector head rotation speed can be limited by weight and safety constraints. Conversely, a volume CBCT acquisition and reconstruction enables large axial coverage in one rotation. This reduces the overall scan time and permits breath-hold acquisitions, thereby improving image quality.

FIG. 2A illustrates the integrated hybrid system 10, which includes two nuclear detectors 18, X-ray or CT source 20, and flat panel X-ray or CT detector 22 that is mounted asymmetrically to a common rotation center of the gantry 16. The nuclear detectors are shown in a 180° configuration, such as for a whole-body planar, SPECT, or PET scanning protocol. The CT source 20 emits an asymmetrical beam, such as may be generated using a beam filter, collimator, (not shown) or the like, directed onto the asymmetrically aligned CT detector 22. The CT detector can be moved to a plurality of positions to generate overlapping FOVs 40 of the VOI 42 in order to generate a complete CT image of the VOI. Note that when the gantry has rotated 180°, the radiation beam will image the other half of the VOI.

FIG. 2B illustrates a side view of the system 10, wherein the imaging FOVs between the two systems is common or coincident, requiring little or no movement of the patient, providing commonly registered images due to the similar imaging planes. The gantry can be rotated 360° degrees during the CT acquisition so that an entire projection dataset that encompasses the patient is acquired once the truncated opposing views (180°) are weighted together. The detector 22 can be offset to create overlap between the opposing projections without missing data. Offsetting or misaligning the detector reduces image artifacts by reducing truncated projection data. Reconstruction using algorithms such as the Feldkamp algorithm can then be used to generate volume CT datasets that can be used for either anatomical localization or attenuation correction. Motion of the X-ray source during the rotation can achieve complete sampling, improving the CBCT reconstruction.

FIG. 2C illustrates another side-view of the system 10, wherein the CBCT source 20 is offset toward the gantry 16 to show motion of the CT source along the longitudinal axis through the gantry, in addition to rotation about the circumference of the gantry. The CT source can thus be extended and/or retracted to scan the length of the VOI, in addition to being rotated about the VOI, to generate a complete set of image data from plurality of angles and positions. During rotational movement of the gantry, the nuclear detectors 18 are held stationary relative to the CT source and detector, so that all devices move with the gantry to ensure that the nuclear detectors are kept out of the FOV of the CT heads and vice versa.

FIG. 2D illustrates a side view of the gantry 16 wherein the CT source 20 moves longitudinally parallel to a central longitudinal axis through the gantry, while emitting an X-ray cone beam through the VOI 42. The longitudinal motion of the CT source facilitates scanning the entire VOI, without having to move the VOI, and can be performed while the gantry is rotated (e.g., continuously or in a stepping action) to ensure that no portion of the VOI is missed during the CT scan. Additionally, the detector 22 can be moved longitudinally with the CT source, or can remain stationary. A filter (not shown) can be employed to direct the X-ray beam toward the detector 22, whether the detector is moving or stationary. In this manner, the system 10 mitigates problems that can arise due to incomplete sampling.

FIG. 2E illustrates another side view of the system 10, wherein the CT X-ray source 20 and flat panel detector 22 are in an in-line configuration relative to the nuclear detector heads 18. In this embodiment, a VOI can be imaged using the nuclear detector heads and the CT source and detector sequentially (in either order).

FIG. 3 is an illustration of another embodiment of the imaging system 10 with a collimator and filter device 50 for directing all or a portion of a cone-shaped X-ray beam to an offset flat panel detector. The system includes the gantry 16, which receives a pallet (not shown) that is supported by a table support (not shown) as it is inserted into an imaging region of the gantry. A pair of nuclear detectors 18 (e.g., SPECT detectors, PET detectors, etc.) are movably positioned on the gantry, along with the X-ray source 20 and the flat panel detector 22. The X-ray source includes a heat exchange device 52 for dissipating heat when the X-ray source is in use. Additionally, a scatter grid 54 is positioned between a VOI (not shown) and the flat panel detector 22. The scatter grid absorbs scattered or attenuated X-rays while letting primary X-rays through to the detector in order to improve X-ray detection.

A patient motion detector 56 detects patient motion, which can trigger adjustment of the CT and/or nuclear imaging detectors to ensure that the VOI of the patient remains within the FOVs thereof. For instance, detected patient motion can trigger a control server 58 and/or a gantry motion controller 60 to initiate movement of the detectors 18 and/or CT source and detector system and/or the patient pallet, respectively, supplies power to maintain the patient in the FOV 40.

An X-ray generator 62 supplies power to the X-ray source 20 to generates X-rays to be emitted through the source during a CT scan. The X-ray generator is additionally coupled to an X-ray controller 64 that signals the X-ray generator to generate X-rays at appropriate times, with appropriate intensity, etc., during the CT scan. The controller 64 is also coupled to a command processor 66 (with a power supply) that receives detected X-ray information from the flat panel detector 22 and provides power thereto. The command processor is additionally coupled to the gantry and to a SPECT-CT acquisition component 68 that receives detected SPECT and CT data. A workstation 69 receives acquired data and includes reconstruction processors and memory (not shown) for reconstructing CT and nuclear images of the VOI or patient.

FIG. 4 illustrates the system 10 configured in a geometry that is typically used during a nuclear cardiology exam. The CT source 20 is positioned on the gantry in a manner that does not impede motion of the nuclear detectors 18 into a 90° orientation, relative to each other, which is desirable when performing a cardiology scan. The nuclear detectors are laterally (in the depicted orientation) moveable to permit the CT source to emit an X-ray beam for detection by the flat panel detector 22 when desired.

FIG. 5 illustrates another embodiment of the system 10, wherein the nuclear detectors 18 (e.g., SPECT or PET), the CT source 20, and the flat panel detector 22 are movably mounted on tracks that facilitate positioning the devices at desired locations during CT and/or nuclear scans. The nuclear detector heads are mounted to a frame that moves along a circular path. The nuclear detectors translate along the sections of the frame, which move closer and further from each other to move the detector heads in a controlled, complex path about the gantry 16. The X-ray source and detector move on circular path around the gantry and are attached thereto by retractable arms that move along frame sections perpendicular to the nuclear detectors and the central axis through the gantry (e.g., up and down in the rotational orientation of FIG. 5). The motion of a retractable extender arm, as it unfolds, is employed to automatically lock for the arm to lock the X-ray detector in a desired position (shown in a stowed or folded position in FIG. 5). In one embodiment, the flat panel detector is attached to a linear slider arm that allows the detector to fold and unfold. The arm is attached to a beam that moves in a circular path and includes an automatic mechanical lock. In this manner, the system 10 mitigates a need for manual locking of the detector 22.

FIG. 6 is a perspective view of the system 10, wherein the flat panel detector 22 is in its operational position, extended outward on an extender arm 70 that is lockably coupled to a mount 72 that couples the extender arm and flat panel detector to the gantry 16. The CT source 20 emits an X-ray beam across an FOV to the flat panel detector while nuclear detectors 18 are positioned out of the way (e.g., off to the side). In the illustrated view, the extender arm extends outward from the page.

FIG. 7 is a perspective view of an automatic locking mechanism 80 for locking the flat panel detector in one or more positions, shown with the extender arm 72 in its extended position. The mechanism includes the mount 70 with the extender arm 72 coupled thereto in a hinged arrangement. The extender includes a slider plate 82 with a plurality of extendible sliders 84 along which the slider plate moves when being extended. At least one slider 84 is coupled to a motion translator 86 that translates the linear motion of the slider into rotational motion. In one embodiment, the motion translator is a gear that is turned by a rack and pinion system (not shown) inside the slider, such that when the slider is extended, the gear rotates in a first direction, and when the slider is retracted the gear rotates in an opposite direction.

The hinged coupling between the mount 70 and the extender arm 72 includes a pin 90 that extends through the ends of an upper and lower portion of the extender arm and through a plurality of hinge segments 92. The gear is in mechanical contact with a locking pin screw 88, and when the gear rotates in the first direction, it causes the locking pin screw to turn and extend a locking pin 94. The locking pin is received by a bore 96 and locks the extender arm 72 in position when the detector is fully extended.

FIG. 8 illustrates the automatic locking mechanism 80 for the flat panel CT detector in its stowed position. The extender arm 72 is stowed against the mount 70 (e.g., the extender arm 72 has been pivoted about the hinge pin 90 to a stowed position). The slider plate 82 is fully retracted into the extender arm 72.

FIG. 9 illustrates the automatic locking mechanism 80 in its fully extended position. The extender arm 72 is pivoted about the hinge pin 90 outward from its stowed position against the mount 70, approximately 90°. The slider plate is extended outward from its stowed position in the extender arm. The motion of the slider plate is translated into rotational motion that actuates a locking pin screw, which extends a locking pin into a receiving bore to lock the extender arm and slider plate in the extended position.

FIG. 10 illustrates the hinge portion of the automatic locking mechanism 80 when the extender arm 72 is in its extended position. The extender arm is rotated outward, about the hinge pin 90, from the mount 70. When the slider plate 82 is extended outward partially from the extender arm, a slider 84 actuates a first motion translator 86 to translate the linear motion of the slider into rotational motion that causes a locking pin screw 88 to be threaded out of a first receiving bore 96. The extender arm is then pivoted 90° outward from the mount, and the slider plate is fully extended from the extender arm. The complete extension of the slider plate causes the slider to engage a second motion translator 87, which causes the locking pin screw 88 to extend the locking pin 94 into a second receiving bore 98, which locks the extender arm into its extended position.

The following example illustrates the movement of the extender arm relative to the preceding figures. The automatic locking assembly for the flat panel detector is stowed in a position as shown in FIGS. 5 and 8. The locking pin 94 is engaged in the first receiving bore 96 in the corresponding hinge mating part. Thus, the extender arm 72 is locked in the folded position. As sliders 84 start to move out linearly to a first position, a motion translator 86 translates the linear motion to rotary motion, causing the locking pin screw 88 to be threaded out of the first receiving bore 96. At this point only portion of the travel of the slider plate is consumed, and the hinge is unlocked. The arm is then rotated approximately 90°, and the slider plate of the extender arm is pulled further out to a completely extended, or operational, position causing a second motion translator 87 to engage and rotate the screw 88 in an opposite direction to insert the locking pin into the second receiving bore 98. Thus, the hinge is locked again in the extended position as shown in FIGS. 6 and 7.

Accordingly, locking is achieved by translating the linear motion to rotary motion through a mechanism such as rack and pinion assembly as shown in FIG. 6. As the slider 84 moves in and out, the fine pitch screw system is turned and the locking pin 94 is inserted into one of the precision bores provided in the mating hinge, thereby eliminating a need to manually lock the flat panel monitor in a given position. Additionally, the mechanism provides a safeguard against an operator failing to lock the detector in position, because the mechanism automatically locks the detector in position.

In another embodiment, a power drive component (not shown) is included to perform automatic two-stage movement of the slider plate and rotation of the extender arm. The power drive can be controlled from a user interface (e.g., a computer or workstation) to move the detector between stowed and operational positions.

In another embodiment, a method of operating the system includes rotating the nuclear detector heads 18, the X-ray source 20, and the X-ray detector 22 around the patient pallet 14 such that the X-ray source and the nuclear detectors have overlapping or coincident fields of view. According to the method, the detector is locked in the operational position when CT acquisition is occurring, and locked in the stowed position when CT acquisition is not occurring (e.g., during nuclear image data acquisition or when the system is not in use. During CT imaging, truncated X-ray data of portions of the VOI 42 of a patient are collected such that views of the VOI are collected form 180° opposite orientations as the gantry 16 rotates. For instance, as the gantry rotates through a 180° point opposite its starting point, the X-ray source and detector begin generating opposing views of the VOI. In this manner, a complete data set is ensured, and redundant data can later be removed, before image reconstruction. Additionally, the X-ray detector is locket in place (e.g., in its operational position opposite the X-ray source) during CT acquisition. Once CT acquisition is complete, the X-ray source is folded out of the way, and the X-ray detector is folded and locked in a stowed position so that nuclear imaging data acquisition can begin. For instance, the detector is mounted to the slider plate 82, which is extended out of the extender arm 72 during CT operation. The slider plate can be retracted from the fully extended position to a partially extended position, and linear motion during the retracting of the plate can be translated into rotational motion by the motion translator 87. The rotational motion causes the locking pin screw 88 to turn, which pulls the locking pin out of the receiving bore 98 to unlock the detector from the operational position. Once the pin is out of the receiving bore 98, the extender arm is folded back against the mount 70. At this point, the slider plate is fully retracted into the extender arm, and the motion translator 86 translates the linear motion of the slider 84 into rotational motion that is applied to the locking pin screw, causing the locking pin to be inserted into the receiving bore 96 to lock the detector in the stowed position. The above actions can be performed in reverse to unlock the detector from the stowed position and lock it in the operational position whenever CT acquisition is to be performed.

FIG. 11 is an illustration of the gantry 16 with the nuclear detectors 18 and the radiation source 20, which is shown opposite the flat panel X-ray detector 22. The flat panel detector 22 is shown in its stored position, in the wall of the rotating gantry portion 26. By storing the flat panel detector in this manner, the flat panel detector 22 is out of the path of the nuclear detectors 18. Moreover, the flat panel detector is protected during, for example, collimator exchange, bed imaging, QC tuning of the nuclear detectors, as well as during shipping.

FIG. 12 is an illustration of the gantry 16, showing the nuclear detectors 18 and the radiation source 20 with the flat panel detector 22 deployed. An extender arm 72′ is folded outward from its stowed position in the surface of the gantry, and the flat panel detector is further folded outward from the extender arm so that a radiation-receiving surface thereof is facing the radiation source 20.

FIGS. 13A-D illustrate top-down views of the flat panel detector 22 and extender arm 72′ in various stages of deployment. In FIG. 13A, the flat panel detector 22 is stored in a folded position against the extender arm 72′, which is also in a folded stowed position.

In FIG. 13B, the flat panel detector 22 has been folded or rotated outward from the extender arm 72′ about a first pivot or hinge 110. The extender arm 72′ has been rotated or folded outward from its stowed position about a second pivot or hinge 112.

In FIG. 13C, the flat panel detector 22 and the extender arm 72′ are in fully extended positions, having been rotated outward from the stowed position to an operational position in which the radiation-receiving surface of the flat panel detector is oriented to receive radiation from a radiation source (e.g., positioned opposite an examination region of the gantry).

In FIG. 13D, the flat panel detector 22 and the extender arm 72′ are in a locked extended position. For instance, an operator pulls a handle 120 out from its stowed position in the extender arm 72′ to lock the detector 22 in position. When the handle 120 is pulled outward, it activates a cam 122 in the extender arm, which in turn exerts a force on one or more balls or bearings 124, 126 positioned in one or more tracks 127, 128 internal to the extender arm 72′. In one embodiment, the tracks include a force transferring means (e.g., springs, rods, or the like) that transfer force between the balls upon activation of the cam. For instance, upon the cam exerting pressure on the ball 126, force is transferred via the track 127 to ball 130, which is in turn exerts a stopping force on pivot point 110, preventing the flat panel detector 22 from moving from its locked position. Similarly and concurrently, activation of the cam exerts pressure on ball 24, which transfers a force to a ball plunger 132 via the track 128. The ball plunger thus pushes a ball or bearing 134 into a ball-receiving groove 136 in the pivot point 112 to prevent the extender arm 72′ from moving during operation. In this manner, the extender arm and flat panel detector are accurately, repeatably, and securely locked in an extended operational position by the dual-pivot point locking arrangement.

FIG. 14 illustrates an embodiment of the system 10′ with the lockable extender arm and flat paned detector assembly in an extended or operational position. The system 10′ includes the subject support 12 with a patient pallet 14 for translating a patient into and out of the examination region of the gantry 16. The pair of nuclear detector heads 18, the radiation source 20, and the flat panel detector 22 are mounted on the gantry 16. A monitor 24 is provided for viewing images of the subject generated by the system 10′. When not in use, the flat panel detector 22 is stowed into a receiving cavity 150, out of the way of the nuclear detectors 18. It will be appreciated that the components of the system 10′ may be similar or identical to the components of the system 10 described with regard to FIGS. 1-5, and may further employ the extender arm 72′ of FIGS. 12-13D.

FIGS. 15-24 illustrate a locking arrangement that uses the principals of a bell crank mechanism to convert an applied turning force of less than or equal to 180° into positive, constant-force, multidirectional, independent, self-locking forces used for controlling mechanical locks. The arrangement is also useful in similar locking applications or to provide anti-backlash features for systems where a positive constant-force is desired, such as on an articulating arm for a nuclear detector or the like. It will be understood that the locking arrangement and articulating arm described with regard to FIGS. 15-24 can be employed with any of the imaging systems described herein, as well as with any other devices that may require a lockable articulating arm. For instance, the articulating arm can be coupled to the rotating gantry, the detector heads, the hybrid imaging device, etc., of the preceding figures and description.

FIG. 15 illustrates a positive force locking mechanism 200 that includes a pair of independent spring-forced actuators 202. Each actuator 202 is coupled to a first flange 203 by a fastener (not shown), with a spring mechanism 204 (e.g., a compression spring, spring washer(s), etc.), and to a second flange 203 by a pivot pin 205. The flanges and actuators are connected in this manner to form a ring around a shank 206, wherein each actuator 202 is pivotally connected with the flange at one end and via a spring at the other end. Each actuator further includes a pin 207 to which a sliding cam lock linkage (not shown) is pivotably coupled. The sliding cam lock linkage thus forms a bell crank that is pivotably connected to the actuator in such a manner that as the bell crank moves over center, the spring element 204 compresses to absorb the forces which would otherwise cause backlash.

FIG. 16 is an exploded view of the locking mechanism 200, which is employed in a bell crank type mechanism whose shaft 206 is connectable to a handle (not shown) in a unique, miniaturized fashion the allows the handle to be used within a compact zone and with minimal turning for locking and unlocking. The application of a compression spring 210 and/or spring washers 212 used in a specific arrangement gives a smooth, progressive feel to the handle movement while mitigating a danger of jerking the handle away from the operator.

Springs 210 or spring washers 212 are selected depending on calculated forces required. The spring mechanisms on either side of the locking mechanism 200 may have different spring constants, to effectuate different force magnitudes depending on the force desired for each locking application. Pins 207 are press-fit in, while the individual actuators 202 are slip-fit on pivots 205. The shank 206 can be keyed or can employ any other means of mechanical coupling. The spring or spring washers are held in by a screw 214 or other fastening means, which limits the range over which the actuator 202 can pivot.

In one embodiment, the springs or washers compress over a very short distance, about 0.15 inches, primarily over the last 5° or so of locking handle rotation. With this arrangement, hysteresis is minimized, there is virtually zero play, and backlash is mitigated.

FIG. 17 illustrates an articulating arm linkage assembly 240, which includes the locking mechanism 200. The locking mechanism 200 is coupled to a hinged high-force sliding lock 242, and is shown in an unlocked position. A high-force locking pin 244 on each side (top and bottom) of the articulating arm 240 is in an unlocked state because a slide bar 246 is in a retracted state when the locking mechanism is unlocked.

By placing the springs between the actuators and the flanges, and not in the cam linkages, snapback is eliminated. Additionally, the bell crank over-center design of the locking mechanism 200 facilitates zero-play locking of the articulating arm.

FIG. 18 illustrates the articulating arm 240 in a locked state, wherein a bell crank 241 has been pivoted about the locking mechanism 200, and the sliding lock 242 has been extended, into a locked position. An actuator 202 coupled to a bell crank slide bar 246 has been rotated about the shank 206, thereby extending the bell crank 246, which in turn rotates a lever arm 247 to rotate a pivot pin (not shown) whose rotation causes a linkage (not shown) to urge the locking pin 244 into an extended or locked position. It will be appreciated that the locking device 240 is symmetrical, such that the bottom side thereof (not visible in FIGS. 17 and 18) is identical to the top side as illustrated. Thus, there are two bell crank 241 and sliding lock 242 linkages, two locking mechanisms (one at each end of the shank 206), two locking pins 244, two crank 246 and lever arm 247 linkages, and so on.

A handle 250 is illustrated in the locked position, and is coupled to the shank 206 to rotate it. The handle 250 can be rotated 180° into the unlocked position, causing the shank to rotate 180°, which in turn causes the locking mechanism(s) to rotate the bell cranks 241, 246 and retract the sliding lock 242 and lever arm 247, thereby unlocking the pins 244 and permitting the locking device to move freely to position a detector or other device coupled thereto. For example, the articulating arm 240 can be coupled to a gantry (not shown) by an axle or pin 252, and to a detector head (not shown) by an axle or pin 254.

FIG. 19 illustrates the articulating arm 240 with the handle 250 positioned approximately halfway between the locked and unlocked positions. As the handle 250 is moved to the locked position (e.g., to the left relative to the page in FIG. 19), the locking mechanism 200 is rotated clockwise, causing the bell crank 241 to push the sliding lock 242 to extend outward (as indicated by the dashed directional arrow). The extended end of the sliding lock 242 is received in a corresponding slot or aperture in a gantry (not shown in FIG. 19), and locks the articulating arm 240 in place relative to the gantry. Concurrently, the clockwise rotation of the locking mechanism 200 causes the crank 246 to rotate the lever arm 247, which turns a shaft 260 clockwise. Rotating the shaft 260 causes a lever arm 261 to extend a link 262 that pivots links 263 to extend the locking pins 244 into receiving apertures on a detector head (not shown in FIG. 19) or the like to lock the articulating arm in place relative to the detector head.

It will be appreciated that the articulating arm described in this and other figures has a top portion 264 and a bottom portion 266, each of which includes identical locking mechanisms, and are coupled together symmetrically by the handle 250. The top and bottom portions are further coupled together by a distal portion 268 that includes the locking pins 244.

As the shaft 206 and the handle 250 approach the locked position, the cranks 241, 246 move over center. That is, about 5° before the locked position, the sliding lock 242 and locking pins 244 have firmly engaged the part (e.g., gantry, detector head, etc.) that they engage and can travel no further. With further rotation of the shaft 206, the pivots 207 try to push the bell cranks 241, 246 further until they reach the apex of their rotational travel. To prevent mechanical kickback, the springs/spring washers 204 compress, reaching maximum compression as the pivots 207 go over center. As the shaft and handle move the last 1-2° to the locked position, the springs expand slightly. The amount of remaining spring force determines the force with which the sliding lock 242 pushes outward.

The arm 240 thus locks in four locations to simultaneously activate and maintain a constant, high pressure to the sliding cam lock linkages 242 and pins 244. Each set (pair) of locks has its own spring force requirements, which are controlled by the positive spring-force locking mechanisms 200. The constant positive effort of the mechanisms ensures that the locks hold the articulating arm in a rigid position and function properly.

This articulating arm 240 can be applied to any commercial application where a constant, positive spring force is required. The articulating arm can also be utilized in mechanisms requiring backlash compensation. Tolerance play or component misalignments are absorbed by the springs in the pivoting actuators, and the locking mechanism 200 provides a constant spring force. The spring forces can be fine-tuned by exchanging the springs as required or via testing and results.

In one embodiment, the sliding locks 242 have a moment force of approximately 900 inch-pounds. In another embodiment, the locking pins 244 have a moment force of approximately 500 inch-pounds.

Suitable materials for the articulating arm 240 include 17-4PH and Nitronic 60 series stainless steel, which absorb the stresses induced by the high-forces of the locks and minimize galling or sticking. Additionally, the over-the-center arrangement of the bell crank assembly automatically locks the individual linkages (e.g., the sliding cam lock linkages, cams, etc.) in the articulating arm 240. A positive force is constantly provided to the linkages to absorb negative cancelling backlash, fatigue, tolerance play, misalignment, under or over travel.

FIG. 20 illustrates the articulating arm 240, coupled to a gantry 270 by an axle or pin 252 at one end and to a detector head 272 by an axle or pin 254 at the other end. The articulating arm is in a locked position, such that the handle 250 has been moved into its locked position, rotating the locking mechanism 200 to extend the locking mechanisms 242, 244. The sliding lock 242 is extended into a receiving slot 274 on the gantry, while the crank 246 has caused a sliding pin linkage to extend locking pins (not visible in FIG. 20) into receiving slots on the detector head 270.

FIG. 21 illustrates the articulating arm 240 coupled to the gantry 270 and the detector head 272. The gantry includes one or more hard stops 280 that arrest movement of the articulating arm about the axle 252, and thereby define a movement endpoint at which the articulating arm can be locked into place relative to the gantry. Similarly, the detector head includes one or more hard stops 280 that arrest movement of the articulating arm about the axle 254, and define a movement endpoint at which the articulating arm can be locked in place relative to the detector head.

FIG. 22 illustrates the articulating arm 240 coupled to the gantry 270 and the detector head 272, with two section lines including a first section line A-A and a second section line B-B.

FIG. 23 illustrates section A-A, showing the sliding pin linkage 262 in an extended state, which has urged the locking pins 244 into respective receiving grooves 290. In one embodiment, the grooves 290 have the shape of a truncated cone or the like, which guides the pins into the grooves as they is extended by the pin linkage 244. Once the pins are fully extended, the spring-force of the locking mechanism retains the pins in a locked position in the grooves 290 until the handle of the articulating arm is released.

FIG. 24 illustrates section B-B, showing the articulating arm 240 with the handle 250 in the locked position. The articulating arm abuts one or more hard stops 280 on the gantry 270, which arrest motion of the articulating arm, permitting it to be locked in place while mitigating sagging or swaying of the arm in the locked position.

Although described herein in the context of an articulating arm for locking a detector in place, it will be understood that the articulating arm 240 and/or the locking mechanism 200 is not limited to such use. For example, the articulating arm may be employed to lock a piece of gear or equipment to a rack, a wall, a vehicle, etc. For instance, the arm can be employed to couple a television or other appliance to an interior wall of house, a vehicle (e.g., an RV, a boat, an airplane, etc.), or the like, to lock the appliance in a stowed position (e.g., during periods of non-use or vehicle motion), and to lock the appliance in an operational position during use.

The innovation has been described with reference to several embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the innovation be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof. 

1. A bell-crank locking mechanism including: a first actuator coupled to a first flange via a first spring mechanism, and to a second flange by a first pivot pin; and a second actuator coupled to the second flange via a second spring mechanism, and to the first flange by a second pivot pin; a shank coupled to the first and second flanges; a pin coupled to each actuator; a crank coupled to each pin; a sliding lock coupled to a first crank; a first lever arm couple coupled to a second crank; a shaft coupled to the lever arm and to a second lever arm that is coupled to a pin linkage; first and second pivot links coupled to the pin linkage, which urge first and second locking pins into a locked position when activated by the second lever arm; and a handle that rotates the shank from an unlocked position in which the pins and the first and second cranks are in a retracted position, through a center position of the pins in which the cranks reach maximum extension and the spring mechanisms are at maximum compression, to an over-center locked position in which the spring mechanisms are partially compressed.
 2. The bell-crank locking mechanism according to claim 1, wherein the bell-crank locking mechanism is formed of 17-4PH stainless steel.
 3. The bell-crank locking mechanism according to claim 1, wherein the bell-crank locking mechanism is formed of Nitronic 60 series stainless steel.
 4. The bell-crank locking mechanism according to claim 1, employed in an articulating arm.
 5. The bell-crank locking mechanism according to claim 4, wherein the sliding lock is extended to place the articulating arm in a locked position relative to a gantry.
 6. The bell-crank locking mechanism according to claim 5, wherein a the first lever arm is extended and causes the pin linkage push the pivot links outward to urge locking pins outward from the articulating arm to place the articulating arm in a locked position relative to a detector head.
 7. The bell-crank locking mechanism according to claim 6, wherein the detector head is one of an X-ray detector and a single photon emission computed tomography (SPECT) detector head.
 8. A lockable articulating arm, including: a top portion and a bottom portion, each of which includes: a positive spring-force locking mechanism including: a first actuator coupled to a first flange via a first spring mechanism, and to a second flange by a first pivot pin; and a second actuator coupled to the second flange via a second spring mechanism, and to the first flange by a second pivot pin; wherein the flanges are coupled to a shank, which is further coupled to a handle; wherein each actuator is coupled to a respective pin; and a bell crank, coupled to a first pin on the first actuator, that extends a sliding lock locks the articulating arm relative to a gantry when the handle is in the locked position; and a second bell crank, coupled to a second pin on the second actuator, that causes at least one locking pin to be extended to lock the articulating arm relative to a detector head when the handle is in the locked position; wherein the second bell crank actuates a shaft that extends a sliding pin linkage that urges a pair of locking pins in a distal portion thereof into a locked position, thereby locking the articulating arm relative to the detector head.
 9. The articulating arm according to claim 8, wherein the positive spring-force locking mechanism is formed of 17-4PH stainless steel.
 10. The articulating arm according to claim 8, wherein the positive spring-force locking mechanism is formed of Nitronic 60 series stainless steel.
 11. The articulating arm according to claim 8, wherein the handle is moved to a locked position with a force of approximately 12-14 pounds.
 12. The articulating arm according to claim 8, wherein the handle is released from its locked position by application of a force of less than approximately 10 pounds.
 13. The articulating arm according to claim 8, wherein the spring mechanisms compress approximately 0.15 inches when the locking mechanism is in a locked position.
 14. The articulating arm according to claim 8, wherein the sliding lock exerts a locking force of approximately 800-1000 inch-pounds when in a locked position.
 15. The articulating arm according to claim 8, wherein the locking pins exert a locking force of approximately 400-600 inch-pounds when in a locked position.
 16. The articulating arm according to claim 8, wherein the distal portion is lockably coupled to the detector head, and the top portion and bottom portion are symmetrically and lockably coupled to the gantry.
 17. The articulating arm according to claim 8, wherein the detector head includes a pair of hard stops that arrest movement of the articulating arm at a predefined point relative to the detector head, at which the articulating arm is locked in position.
 18. The articulating arm according to claim 8, wherein the gantry includes a pair of hard stops that arrest movement of the articulating arm at a predefined point relative to the gantry, at which the articulating arm is locked in position.
 19. A method of locking a device in each of a stowed position and an extended position, comprising: rotating a handle on an articulating arm approximately 180°, from a locked position to an unlocked position; moving the detector head from a stowed position to an extended position; and rotating the handle from the unlocked position to the locked position; wherein rotating the handle effectuates rotation of a pair of locking mechanisms, each of which extends a sliding lock to lock the articulating arm in position at a mounted end, and extends a lever arm to effectuate movement of a sliding pin linkage that extends a pair of locking pins to lock the articulating arm in position at a device end.
 20. The method according to claim 19, wherein the articulating arm is coupled to a detector head at the device end, and to a gantry at the mounted end. 